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Full text of "Text Book Of Mechanical Engineering"

Smiths Tools.

93

in the side elevation. The power absorbed in running this
machine is very slight, and the speed need not be more than 300
revolutions per minute. A fan, on the other hand, to be effective,
must be driven at a great velocity, say from 1000 to 2000
revolutions per minute; more shafting and pullies are required,
as shewn in Fig. 93, and the percentage of loss by friction is
consequently high. The blower is, however, very noisy.
# Tools.—Among these we must first mention the Anvil,
Fig. 96. It is made of wrought iron, and has a surface of steel
about a quarter of an inch thick welded on at A to form the top
face; B is the beak or horn; c and D are square holes to receive
* bottom' tools, and E E are used in punching. At Fig. 968 is
illustrated a French anvil. It is not provided with any holes,
the swage block (described later) serving instead.

Two kinds of Hammer are required: the hand hammer
weighing two-and-a-half to three pounds, for the smith; and the
sledge hammer, used by his helper, weighing from eight to four-
teen pounds, and even more. If the sledge is only worked by lifting
over the shoulder, a short handle' is used, say three feet long, but,
when swung, in making heavy forgings, a long shaft is required,
the right hand being drawn inward to the end as the hammer
approaches the work, thus giving the latter the full effect of the
stored energy.

Other tools, shewn in Fig. 97, are principally for the purpose
of finishing work for which the hammer alone would be in-
sufficient They often go in pairs, as top and bottom tools, the
smith holding the first by means of a hazel rod wrapped round it,
while the second is placed upright in one of the square holes in the
anvil. A A are chisels^ B B fullers, c is a flat-face orflatter', D a punch^
and E E are swages. The last term is applied to any specially-
shaped top and bottom tools designed for the purpose of finishing
work with greater ease and accuracy to a particular form, such as
round, hexagonal, &c» F is a set hammer, having either a square
or circular face; it is held steadily on the work while being struck,
so that in one sense it is not a hammer at all It is convenient
as a top tool to reduce work or ' set' it down, the anvil serving
as bottom tool G is a 'heading* tool, useful in making the
heads of bolts and pins. It is held by the hand at one end

H